Which technique measures voltage between two electrodes to determine analyte concentration?

Potentiometry is a technique utilized in analytical chemistry to measure the voltage difference between two electrodes immersed in a solution in order to determine the concentration of a specific analyte. The method relies on the Nernst equation, which describes how the voltage corresponds to the concentration of ions in solution. This technique typically employs a reference electrode and an indicator electrode, with changes in voltage reflecting variations in analyte concentration.

In potentiometric measurements, the solution’s composition can affect the electrode potential, and thus, the determined voltage is directly related to the concentration of the analyte of interest. This makes potentiometry particularly suitable for measuring ion concentrations, such as pH, metal ions, and other species, allowing for highly sensitive and specific analyses.

Other techniques mentioned in the options do not measure voltage in the same way. Coulometry involves the measurement of the total electric charge passed through a solution to quantify an analyte, amperometry measures the current flowing through the solution at a set potential, and voltammetry measures current as a function of varying applied voltage but focuses on the response of electrochemical reactions rather than a direct potential measurement like potentiometry.